Earth and road working machines, such as graders, are used primarily to maintain or create a desired ground surface. The operation is typically accomplished by a machine having a mold board or like construction. A mold board is a long scoop-like member having a slight concave surface facing in the direction of travel. The mold board is pushed across the ground or road by the machine to perform a scraping-grading type action. As can be appreciated, such an operation subjects the mold board to harsh treatment, and left unchecked would quickly ruin the mold board. To avoid premature wearing of the mold board, a wear element is secured along the mold board's lower edge.
One common wear element used to protect mold boards is an elongate blade member. The blade members are generally fabricated in three and four foot long increments and bolted end-to-end across the entire lower edge of the mold board. With this construction, the blade forms a continuous working edge which engages the ground surface and protects the mold board. An example of such a blade is disclosed in U.S. Pat. No. 4,770,253 to Hallissy et al. After a certain length of time, the worn blades are replaced instead of the much more costly mold board.
Another common wear element used to protect mold boards involves a modified form of the blade and a plurality of picks. More specifically, the modified blade member is secured to the lower edge of the mold board. Like the wear blades discussed above, these blades are fabricated in three and four foot long increments and positioned end-to-end across the mold board. However, instead of a lower working edge, the blade defines means for securing the picks. The picks are generally bolted to the face of the blade or releasably retained (e.g., by a clip) within a socket defined in the blade. In any event, a plurality of the picks are secured in place along the blade to collectively form a discontinuous working edge for engaging the ground surface. Each pick defines a generally linear edge comprising a segment of the working edge. One example of such a wear element is disclosed in U.S. Pat. No. 4,753,299 to Meyers. In this construction, only the picks generally require replacement. Alternatively, the discontinuous edge can also be formed by a specially configured blade member, such as shown in U.S. Pat. No. 3,192,653 to Socin.
In order to increase the useful life of the wear element, its working edge is often provided with a hardened insert. The insert forms the leading face and at times the bottom face, to maximize the protection afforded the wear element. The inserts are generally brazed to the wear element along one or two mounting faces. The inserts, however, are at times broken off from the wear element. Once the insert is lost, the wear element is quickly worn away and ruined. This results not only in higher maintenance and repair costs, but also increased down time for the machine.